Control system and method for operating an ultrasonic liquid delivery device

Abstract

In a control system and method for operating an ultrasonic liquid delivery device, an ultrasonic waveguide, separate from the housing, is disposed at least in part within an internal chamber of the housing to ultrasonically energize liquid prior to the liquid being exhausted from the housing through an exhaust port. An excitation device is operable to ultrasonically excite the waveguide and a control system controls operation of the liquid delivery device between an excitation mode in which the excitation device is operated at an excitation frequency to excite the ultrasonic waveguide and a ring down mode in which the excitation device is inoperable to excite the waveguide such that the waveguide rings down. The control system monitors the ring down and is responsive to the ring down to adjust the excitation frequency of the excitation device in the excitation mode thereof.

1. An ultrasonic liquid delivery device comprising:
 a housing having an internal chamber, at least one inlet in fluid communication with the internal chamber for receiving liquid into the internal chamber and at least one exhaust port in fluid communication with the internal chamber whereby liquid within the chamber exits the housing at said at least one exhaust port; 
 an ultrasonic waveguide separate from the housing and disposed at least in part within the internal chamber of the housing to ultrasonically energize liquid within the internal chamber prior to said liquid being exhausted from the housing through the at least one exhaust port; 
 an excitation device operable to ultrasonically excite said ultrasonic waveguide; and 
 a control system for controlling operation of the liquid delivery device between an excitation mode in which the excitation device is operated at an ultrasonic excitation frequency to ultrasonically excite the ultrasonic waveguide and a ring down mode in which the excitation device is inoperable to excite the ultrasonic waveguide such that the ultrasonic waveguide is allowed to ring down, the control system being operable to monitor a ring down frequency of said ring down with a feedback sensor and further being responsive to said ring down of the ultrasonic waveguide to adjust the excitation frequency of the excitation device in the excitation mode thereof based at least in part on the ring down frequency. 
 
     
     
       2. The ultrasonic liquid delivery device set forth in  claim 1  wherein the control system is operable to determine a ring down frequency of the waveguide during said ring down mode, the control system being responsive to said ring down of the ultrasonic waveguide to adjust the excitation frequency of the excitation device in the excitation mode thereof to be within at least about 10 Hz of the ring down frequency. 
     
     
       3. The ultrasonic liquid delivery device set forth in  claim 1  further comprising a valve member moveable relative to the housing between a closed position in which liquid within the internal chamber is inhibited against exhaustion from the housing via the at least one exhaust port, and an open position in which liquid is exhausted from the housing via the at least one exhaust port, in the open position of the valve member the control system operating in the excitation mode of the liquid delivery device and in the closed position of the valve member the control system operating in said ring down mode of said liquid delivery device. 
     
     
       4. The ultrasonic liquid delivery device set forth in  claim 3  wherein the control system is further operable to control movement of the valve member between its open and closed positions. 
     
     
       5. The ultrasonic liquid delivery device set forth in  claim 3  wherein the ultrasonic waveguide is separate from and moveable relative to the valve member. 
     
     
       6. The ultrasonic liquid delivery device set forth in  claim 1  wherein in the excitation mode of said liquid delivery device the control system sends an ultrasonic frequency drive signal having an excitation frequency to the excitation device to ultrasonically vibrate said excitation device at said excitation frequency, and in the ring down mode of said liquid delivery device the control system ceases sending an ultrasonic drive signal to the excitation device and receives a ring down signal from said excitation device corresponding to the ring down of the ultrasonic waveguide. 
     
     
       7. The ultrasonic liquid delivery device set forth in  claim 6  wherein the control system ceases sending the frequency drive signal to the excitation device at a peak of said signal. 
     
     
       8. The ultrasonic liquid delivery device set forth in  claim 6  wherein the ultrasonic frequency drive signal comprises an analog sine wave. 
     
     
       9. The ultrasonic liquid delivery device set forth in  claim 6  wherein the ultrasonic frequency drive signal comprises a digitally stepped sine wave. 
     
     
       10. A method for controlling an ultrasonic liquid delivery device, said device comprising a housing having an internal chamber, at least one inlet in fluid communication with the internal chamber for receiving liquid into the internal chamber and at least one exhaust port in fluid communication with the internal chamber whereby liquid within the chamber exits the housing at said at least one exhaust port, and an ultrasonic waveguide separate from the housing and disposed at least in part within the internal chamber of the housing to ultrasonically energize liquid within the internal chamber prior to said liquid being exhausted from the housing through the at least one exhaust port, said method comprising:
 ultrasonically exciting the ultrasonic waveguide at an excitation frequency; 
 ceasing to excite the ultrasonic waveguide to allow the ultrasonic waveguide to ring down; 
 determining, with a feedback sensor, a ring down frequency of the ultrasonic waveguide as the waveguide rings down; and 
 adjusting the excitation frequency in response to the ring down frequency being different from the excitation frequency of said ultrasonic waveguide. 
 
     
     
       11. The method set forth in  claim 10  further comprising, after determining a ring down frequency of the ultrasonic waveguide, determining the difference between the ring down frequency and the excitation frequency and comparing said difference to a predetermined tolerance range for said difference, the adjusting step comprising adjusting the excitation frequency in response to said difference being outside said tolerance range. 
     
     
       12. The method set forth in  claim 11  wherein the adjusting step comprises adjusting the excitation frequency in response to said difference being greater than 10 Hz. 
     
     
       13. The method set forth in  claim 10  wherein the ultrasonic liquid delivery device further comprises a valve member moveable relative to the housing between a closed position in which liquid within the internal chamber is inhibited against exhaustion from the housing via the at least one exhaust port, and an open position in which liquid is exhausted from the housing via the at least one exhaust port, the method comprising:
 positioning the valve member in its open position to permit liquid to be exhausted from the housing, the step of ultrasonically exciting the ultrasonic waveguide at an excitation frequency being performed with the valve member in its open position. 
 
     
     
       14. The method set forth in  claim 13  further comprising positioning the valve member in its closed position after exhausting liquid from the housing, the step of ceasing to excite the ultrasonic waveguide to allow the ultrasonic waveguide to ring down being performed at least in part with the valve member in its closed position. 
     
     
       15. The method set forth in  claim 10  wherein the liquid delivery device further comprises an excitation device operable to ultrasonically excite the ultrasonic waveguide, the step of ultrasonically exciting the ultrasonic waveguide at an excitation frequency comprising generating an ultrasonic frequency drive signal and delivering said signal to the excitation device to operate said excitation device at said ultrasonic frequency to thereby ultrasonically excite the ultrasonic waveguide. 
     
     
       16. The method set forth in  claim 15  wherein the step of ceasing to excite the ultrasonic waveguide to allow the ultrasonic waveguide to ring down comprises ceasing to deliver the ultrasonic frequency drive signal to the excitation device. 
     
     
       17. The method set forth in  claim 16  wherein ring down vibration of the waveguide drives vibration of the excitation device at the ring down frequency of the waveguide, the step of determining the ring down frequency of the waveguide comprising determining the vibration frequency of the excitation device during ring down of the waveguide. 
     
     
       18. The method set forth in  claim 17  wherein the step of determining the vibration frequency of the excitation device during ring down of the waveguide comprises generating an electrical signal corresponding to the vibration of the excitation device during ring down of the waveguide and determining the frequency of said electrical signal. 
     
     
       19. The method set forth in  claim 16  wherein the step of ceasing to deliver the ultrasonic frequency drive signal to the excitation device control system is performed at a peak of said drive signal. 
     
     
       20. The method set forth in  claim 15  wherein the ultrasonic frequency drive signal comprises an analog sine wave. 
     
     
       21. The method set forth in  claim 15  wherein the ultrasonic frequency drive signal comprises a digitally stepped sine wave. 
     
     
       22. An ultrasonic liquid delivery device comprising:
 a housing having an internal chamber and at least one exhaust port in fluid communication with the internal chamber of the housing whereby liquid within the chamber exits the housing at said at least one exhaust port; 
 a valve member moveable relative to the housing between a closed position in which liquid within the internal chamber is inhibited against exhaustion from the housing via the at least one exhaust port, and an open position in which liquid is exhaustible from the housing via the at least one exhaust port; 
 an ultrasonic waveguide for ultrasonically energizing liquid within the internal chamber prior to said liquid being exhausted from the housing through the at least one exhaust port in the open position of the valve member; 
 an excitation device operable to ultrasonically excite said ultrasonic waveguide; and 
 a control system controlling operation of the valve member to position the valve member from its closed to its open position to thereby exhaust liquid from the housing, said control system further controlling operation of the excitation device to ultrasonically excite said ultrasonic waveguide, in the closed position of the valve member the control system initiating operation of the excitation device to ultrasonically excite said ultrasonic waveguide prior to controlling the valve member to move to its open position. 
 
     
     
       23. The device set forth in  claim 22  wherein the ultrasonic waveguide is separate from the valve member. 
     
     
       24. The device set forth in  claim 22  wherein the ultrasonic waveguide is separate from the housing. 
     
     
       25. The device set forth in  claim 24  wherein the waveguide is disposed at least in part within the internal chamber of the housing. 
     
     
       26. The device set forth in  claim 22  wherein in the closed position of the valve member the control system initiates operation of the excitation device to ultrasonically excite said ultrasonic waveguide in the range of about 0.1 milliseconds to about 5 milliseconds prior to controlling the valve member to move to its open position. 
     
     
       27. The device set forth in  claim 22  wherein the liquid delivery device comprises an ultrasonic fuel injector. 
     
     
       28. A method of operating an ultrasonic liquid delivery device comprised of a housing having an internal chamber and at least one exhaust port in fluid communication with the internal chamber of the housing whereby liquid within the chamber exits the housing at said at least one exhaust port, and a valve member moveable relative to the housing between a closed position in which liquid within the internal chamber is inhibited against exhaustion from the housing via the at least one exhaust port, and an open position in which liquid is exhaustible from the housing via the at least one exhaust port, said method comprising:
 positioning the valve member in its closed position; 
 delivering liquid into the internal chamber of the housing; 
 ultrasonically energizing said liquid within the internal chamber of the housing with the valve member in its closed position; and 
 repositioning the valve member toward its open position to permit liquid to be exhausted from the housing via the at least one exhaust port, the step of ultrasonically energizing the liquid within the internal chamber of the housing with the valve member in its closed position being initiated prior to repositioning the valve member toward its open position. 
 
     
     
       29. The method set forth in  claim 28  wherein the step of ultrasonically energizing the liquid is initiated in the range of about 0.1 milliseconds to about 5 milliseconds prior to repositioning the valve member toward its open position. 
     
     
       30. The method set forth in  claim 28  further comprising continuing to ultrasonically energize liquid within the internal chamber of the housing with the valve member in its open position. 
     
     
       31. The method set forth in  claim 30  further comprising, after liquid is exhausted from the housing, the steps of ceasing to ultrasonically energize liquid within the internal chamber of the housing, and repositioning the valve member back toward its closed position. 
     
     
       32. The method set forth in  claim 28  wherein the liquid delivery device further comprises an ultrasonic waveguide disposed at least in part within the internal chamber of the housing, and an excitation device operable to ultrasonically excite the ultrasonic waveguide, the step of ultrasonically energizing liquid within the internal chamber of the housing with the valve member in its closed position comprising operating the excitation device to ultrasonically excite said waveguide, operation of the excitation device being initiated prior to the valve member being repositioned toward its open position. 
     
     
       33. The method set forth in  claim 28  wherein the method is for controlling operation of the device according to a single ejection event comprising multiple positionings of the valve member from its closed position to its open position and then back to its closed position, the step of ultrasonically energizing the liquid within the internal chamber of the housing with the valve member in its closed position being initiated prior to each repositioning of the valve member from its closed position toward its open position. 
     
     
       34. An ultrasonic liquid delivery device comprising:
 a housing having an internal chamber, at least one inlet in fluid communication with the internal chamber for receiving liquid into the internal chamber and at least one exhaust port in fluid communication with the internal chamber whereby liquid within the chamber exits the housing at said at least one exhaust port; 
 an ultrasonic waveguide separate from the housing and disposed at least in part within the internal chamber of the housing to ultrasonically energize liquid within the internal chamber prior to said liquid being exhausted from the housing through the at least one exhaust port; 
 an excitation device operable to ultrasonically excite said ultrasonic waveguide; and 
 a control system for controlling operation of the liquid delivery device between an excitation mode in which the excitation device is operated at an ultrasonic excitation frequency to ultrasonically excite the ultrasonic waveguide and a ring down mode in which the excitation device is inoperable to excite the ultrasonic waveguide such that the ultrasonic waveguide is allowed to ring down, the control system being operable to monitor said ring down and further being responsive to said ring down of the ultrasonic waveguide to adjust the excitation frequency of the excitation device in the excitation mode thereof, wherein in the excitation mode of said liquid delivery device the control system sends an ultrasonic frequency drive signal having an excitation frequency to the excitation device to ultrasonically vibrate said excitation device at said excitation frequency, and in the ring down mode of said liquid delivery device the control system ceases sending an ultrasonic drive signal to the excitation device at a peak of said signal and receives a ring down signal from said excitation device corresponding to the ring down of the ultrasonic waveguide.